Conventional display devices present images on a two dimensional screen. Common displays are cathode ray tubes (CRTs), liquid crystal displays (LCDs), Field Effect Displays (FEDs), and projection displays, among others. Various attempts have been made to incorporate the illusion of depth on two dimensional displays. These methods achieve the illusion of depth by presenting separate images to each eye of the viewer.
The main methods of achieving the illusion of depth have been stereoscopic and auto-stereoscopic displays.
Stereoscopic displays generally use composite images which are split into two images by glasses worn by the viewer. Each eye piece in the glasses will allow certain characteristic light patterns through to each individual eye. Popular methods of achieving this are through the use of polarisation, shutter glasses, defraction grating, multi colour lens, and dual screen head mounted displays.
Auto-stereoscopic displays do not use glasses but instead generally use a lens configuration in which stereo images on a screen are aligned through lens or optical grating to focus in the general area of the viewers' individual eyes.
One main problem associated with these displays reside in the inability to gain convergence of stereo images to match the distance between the viewers' eyes. Incorrect convergence leads to disorientation and possible nausea when viewed for extended periods. In the case of most auto-stereoscopic displays the viewing area is limited to the focal length of the lens used. This limits the number of simultaneous viewers of a single screen. Traditional auto stereoscopic displays are limited to one or two simultaneous viewers. While, traditional stereoscopic displays require all users to wear glasses. In addition each of these methods require head tracking devices to be incorporated in order to achieve motion parallax.
Certain designs have been made that use multiple levels of images.(U.S. Pat. No. 4,736,214) These designs incorporate reflected images from single or multiple sources. The reflected images of these designs produce “ghostly” multi layered images, which are generally unacceptable for normal lighting conditions.
Images transmitted to these display devices via antenna, VCR, cable etc. are generally compressed during transmission. It is common for these compression algorithms to compress based on pixel change between consecutive frames.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.